Desktop 3D printers are rapidly growing in popularity and use in homes, offices, classrooms, and laboratories, but they have recently been shown in one pilot study to emit large amounts of very small particles into indoor environments. Exposure to these small particles may be of concern for human health, as they can penetrate deep into the lungs and may lead to respiratory irritation, exacerbation of asthma symptoms, or cardiovascular problems. There may be emissions of gas-phase compounds of concern as well. Therefore, this project will use a combination of laboratory chamber testing, modeling, and field measurements in occupational settings to characterize emissions of particulate matter and volatile organic compounds (VOCs) resulting from the operation of five commercially available desktop 3D printers. This project will also measure the effectiveness of a custom-built filtration attachment for reducing emissions. Once emissions are evaluated in the laboratory, we will perform indoor air quality modeling to simulate the impacts of desktop 3D printers on particle and VOC concentrations in a number of workplace settings. Finally, the models will be validated with a small number of field studies. We aim to better characterize emissions of a number of pollutants from these devices and test a prototype filtration device that 3D printer users can rely on to significantly reduce emissions and hopefully avoid any potential negative health effects associated with exposure to these pollutants. We will also make our filter designs available for free online so other users can experiment with their own filtration systems to fit their own make and model of 3D printer. This research will specifically address worker exposures to pollutants in a variety of industry sectors that utilize 3D printers, including those covered by NIOSH sector programs in Manufacturing and Services. This research will also address a number of cross-sector programs: 1. By characterizing emissions of gases and particles from 3D printers and resulting concentrations in workplaces, this research will address the Exposure Assessment and Nanotechnology cross-sector programs. 2. By evaluating an emission control technology for 3D printers, this research will address both Prevention through Design and Engineering Controls cross-sector programs. 3. If the prototype filtration system is shown to reduce emissions and can be used to effectively reduce concentrations of pollutants inside workplaces, this research may also address Cancer, Reproductive and Cardiovascular Diseases and Respiratory Diseases cross-sector programs.